1. Field of the Invention
This invention relates to a communication terminal such as a facsimile apparatus having a plurality of data transmission functions and to the method description of the related art.
A basic user network interface provided for conventional communication terminals of this kind and connected to a line of the integrated services digital network (ISDN) is capable of connecting, at its maximum capacity, eight units including digital telephone sets and data communication terminals such as facsimile apparatuses. On the other hand, composite terminals in which a digital telephone set, a facsimile and the like are combined can be designed so as to have eight data transmission functions at the maximum and be connected to one basic user network interface.
In the conventional communication terminals, however, analog telephone sets cannot be used by being directly connected to the interface to the ISDN line. If an analog telephone set is connected in parallel with a G (group) 4 facsimile apparatus or the like through an adaptor, it cannot be used easily in practice because there is no means for informing the user of the states of the analog telephone and the line.